Perforation machining of a material for which mechanical machining is difficult is typically performed using an electrolytic machining method, a discharge machining method, or similar. Using an electrolytic machining method is especially preferable for performing perforation machining of such a material having a high aspect ratio.
Incidentally, for example, a cooling hole for passing a coolant medium to cool a turbine blade is formed in the turbine blade of a gas turbine. Then, in order to realize a design that is thermally and aerodynamically optimized, that is, in order to efficiently cool a portion, such as a blade profile, a platform, and the like, that reaches high temperatures, the shape of the cooling hole preferably curves along a geometric shape of the turbine blade.
Here, for example, Patent Document 1 discloses an assembly using an electrochemical machining method enabling the formation of a curved hole in a machined product by using a curved electrode.